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In the equation ax^2 + bx + c = 0, where a, b and c are constants and

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In the equation ax^2 + bx + c = 0, where a, b and c are constants and  [#permalink]

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Updated on: 01 Feb 2019, 23:45
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Question Stats:

37% (01:56) correct 63% (01:17) wrong based on 19 sessions

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In the equation ax^2 + bx + c = 0, where a, b and c are constants and a ≠ 0, what is the value of b?

(1) 3 and 4 are roots of the equation.

(2) The product of the roots of the equation is 12.

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Originally posted by gmat1393 on 01 Feb 2019, 22:57.
Last edited by Bunuel on 01 Feb 2019, 23:45, edited 1 time in total.
Renamed the topic and edited the question.
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Re: In the equation ax^2 + bx + c = 0, where a, b and c are constants and  [#permalink]

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01 Feb 2019, 23:24
gmat1393 wrote:
In the equation ax2 + bx + c = 0, where a, b and c are constants and a ≠ 0, what is the value of b?

(1) 3 and 4 are roots of the equation.

(2) The product of the roots of the equation is 12.

I believe the question is ax^2 + bx + c = 0

IMO A

from 1, when we know that the roots of the equation are 4 and 3, this means their product will be 12

and we can 12 in 1 way, when b = 7, since both roots are +ive

from 2, now when we know that value of roots is 12,

we can get the product in 2 ways when b=7 or b=-7

making this statement insufficient.
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Re: In the equation ax^2 + bx + c = 0, where a, b and c are constants and  [#permalink]

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02 Feb 2019, 00:01
2
$$ax^2 + bx + c = 0$$
(1) 3 and 4 are roots of the equation
$$(x-3)(x-4) = x^2-7x+12 \rightarrow b= -7$$
$$(2x-6)(2x-8) = 4x^2-28x+48 \rightarrow b= -28$$
Not sufficient

(2) The product of the roots of the equation is 12
product of the roots = c/a = 12
Again $$x^2-7x+12 \, and \, 4x^2-28x+48$$ are possible
Not sufficient

Combining both the statements
$$x^2-7x+12 \, and \, 4x^2-28x+48$$ are possible
Or $$b= -7 \, and \, b= -28$$ are possible
Hence E .
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Re: In the equation ax^2 + bx + c = 0, where a, b and c are constants and   [#permalink] 02 Feb 2019, 00:01
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